Evaluation of UHF-RFID Tag Performance Considering Near-Field and Detuning Effects on Various Dielectric and Inhomogeneous Application Surfaces

This paper focuses on the analysis of performance degradation of UHF-RFID tags considering the impact of objects and materials in its immediate proximity. Materials utilized as packaging and container material in logistics and production environments, combined with its contents frequently lead to a complex and inhomogeneous environment. Although it is well known that the surface material and tag positioning have a great impact on the tag antenna, a meaningful rating method for performance evaluation, taking into account the introduced impedance mismatch, as well as the altered radiation pattern is still lacking. Hence, this paper proposes a rating scheme enabling a convenient application-specific tag readability evaluation. The impact of materials, as well as tag positioning on the target object can be evaluated, taking into account the sensitivity of the tag-IC, antenna characteristics and polarization. By utilization of full-wave simulation techniques, the complex near-field effects are determined. Based on the simulation results, the tag readability for a selection of common use-cases is evaluated. Finally, measurements in an anechoic chamber confirm the validity and usefulness of the proposed evaluation.